There is a dwindling availability of natural rosewood. Dalbergia nigra, or Brazilian Rosewood, which is considered to be the finest variety, is virtually unobtainable. Dalbergia latifolia, or East Indian Rosewood, is available on a limited basis in small dimension stock only. The cost of natural rosewood is very high, being about eight times the price of walnut, an available domestic wood which can conveniently be employed as starting material for the present invention.
Natural rosewood has become a rare, expensive, and highly-prized wood. Most uses of rosewood today are for such purposes as decorative inlay work, expensive furniture, musical instruments, expensive paneling, fancy handles, and the like.
Although problems of supply, quality, and cost preclude the use of rosewood in furniture and many other products, the popularity of, and demand for, rosewood has been, and continues to be, very strong. This is evident from many examples seen in furniture, accessory furnishings, musical instruments, sporting goods items, cutlery, and other products. The term rosewood is often used in reference to the finishes on these items.
The demand for rosewood is met in various ways including surface coloring of white woods by painting or staining them a "rosewood" color, the use of rosewood-colored plastics, and the use of white woods impregnated with rosewood colored dyes. None of these methods provides a satisfactory rosewood substitute and all have various shortcomings. Stained wood falls short of the quality of appearance which is obtained in wood which is finished in its natural color without the use of stains. This finish is easily abraded or damaged, revealing the underlying white wood. Plastics are unsatisfactory substitutes.
Several methods have been devised over the years to color-impregnate wood with various colors, including rosewood-like colors. These methods fall into the following general classifications: dye impregnation, dye/resin impregnation, dye/ resin impregnation and compression of wood. In the areas of dye impregnated and dye/resin impregnated woods, when "rosewood" colors are produced, they lack the intensity of the color of natural rosewood. It has also proven impossible to completely impregnate woods with these substances (5). There always remain certain areas in the wood which are impervious to the dyes or dye/resin combinations. This results in unattractive uncolored streaks being visible in the finished material. Ray cells are particularly impervious to dyes and areas of ray fleck figure are present in much of the wood which remains undyed. In an effort to overcome these difficulties, methods have been developed to dye thin sheets of wood veneer, these being more readily impregnated than lumber (5), and then to laminate the veneer sheets into stock of the desired thickness. This material is in common use in the archery industry for bow handles (6), but still fails to overcome the previously-noted shortcomings of dye-impregnated woods. In addition, it has the objectionable characteristic of looking like plywood, which is what it is. This material is suitable for certain specialized applications but its use is not widespread, and it most assuredly is not considered to be a rosewood substitute.
In the area of dye/resin impregnated and compressed wood, in a material generally known as "Compreg", more intense colors than those of previously-described materials are generally achieved. However, the problems associated with dye-impregnated wood, especially unimpregnated areas, remain in this material. In addition, it has the objectionable characteristics of looking like plywood, being extremely hard and heavy, being very brittle, and consisting more of resin than of wood. This material is in common use in the cutlery industry for handle material. However, its use is even more restricted than that of the previously-described laminated material and it is likewise not considered to be a rosewood substitute.
The desirable characteristics of the finest natural rosewood include, in addition to the primary characteristic of its color, susceptibility of polish, hardness, and durability (1,2).
The supply of natural rosewood today is characterized by availability in small dimensions only, inadequate and unreliable supply, and excessive cost.
The finest grade of natural rosewood is generally considered to be the species Dalbergia nigra, or Brazilian Rosewood. This rosewood is believed to excel all other varieties in the fineness, uniformity, depth, and intensity of its color (2). Heretofore it has been impossible to duplicate this color in artificially color-impregnated wood materials.
The art of impregnating wood is well known and widely practiced in industry. However, the complete impregnation of the entire structure and substance of woods is neither known nor practiced. It is of course not necessary or desirable in the wood preservation industry. It is not achieved in dye or dye-resin impregnated wood, as evidenced by the uncolored, unimpregnated areas which still remain in these products.
No Prior Art in this field is known to me except that noted and cited in my prior application of which the present application is a continuation-in-part, and such prior art is not considered relevant to the present invention.
It seems clear that the prior art has not provided any rosewood substitute, or any method of producing the same, much less such a method which is economically and commercially feasible, generally applicable to large wood sizes, and equivalent throughout its composition and substance to rosewood in its degree of rosewood color, darkness, depth, and intensity, which is stable and with no tendency for color bleed-out or fading. It also is apparent that the expense and relative unavailability of natural rosewood now places a suitable and satisfactory rosewood substitute, such as is provided by the present invention, and an economic and commercially-feasible process for the production thereof, into the category of a "long-awaited" development.